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Date: Mon, 25 Mar 2019 17:17:55 +0000 From: "Singh, Brijesh" <brijesh.singh@....com> To: Borislav Petkov <bp@...en8.de>, lijiang <lijiang@...hat.com> CC: "Singh, Brijesh" <brijesh.singh@....com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>, "tglx@...utronix.de" <tglx@...utronix.de>, "mingo@...hat.com" <mingo@...hat.com>, "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>, "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>, "dyoung@...hat.com" <dyoung@...hat.com>, "Lendacky, Thomas" <Thomas.Lendacky@....com>, "bhe@...hat.com" <bhe@...hat.com> Subject: Re: [PATCH 1/3] kexec: Do not map the kexec area as decrypted when SEV is active Hi Boris, On 3/25/19 1:37 AM, Borislav Petkov wrote: > On Mon, Mar 25, 2019 at 09:58:07AM +0800, lijiang wrote: >> For the SEV virtual machine, it maps the kexec memroy area as >> encrypted, so, no need to invoke this function to change anything. > > Look at the code: > > set_memory_decrypted->__set_memory_enc_dec > > It already *does* invoke this function. > By default all the memory regions are mapped encrypted. The set_memory_{encrypt,decrypt}() is a generic function which can be called explicitly to clear/set the encryption mask from the existing memory mapping. The mem_encrypt_active() returns true if either SEV or SME is active. So the __set_memory_enc_dec() uses the memory_encrypt_active() check to ensure that the function is no-op when SME/SEV are not active. Currently, the arch_kexec_post_alloc_pages() unconditionally clear the encryption mask from the kexec area. In case of SEV, we should not clear the encryption mask. >>> if (!mem_encrypt_active()) >>> >>> and heads will spin from all the checking of memory encryption aspects. >>> >>> So this would need a rework so that there are no multiple confusing >>> checks. >> >> About the three functions, here i copied their comment from the arch/x86/mm/mem_encrypt.c >> Please refer to it. > > I know that comment - I have asked for it. Now you go and look at the > code again with your patch applied. >
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